Clays are normally mined from the ground in an aggregated, or deflocculated, state. They must be disaggregated, or deflocculated, into their constituent clay mineral particles in order for further refining and particle size separation to be carried out. In the case of kaolinite, these primary particles are discs with a regular, hexagonal shape. This change in morphology, from the flocculated clay in some amorphous or spherical configuration, to the deflocculated clay with its disc shape, led to the belief that electro-optic methods would provide a novel solution to the present industrial problem of determining the state of deflocculation of concentrated aqueous suspensions of kaolinite.
As early as 1954 electric birefringence was being used to study the physical properties of clay minerals as a function of exchangeable cations [Khan, A. and Lewis, D. R., J.Phys. Chem., 58 (10), 801-804).
In 1959, electric birefringence was used to study the mechanism of flocculation of clay suspensions by polyelectrolytes (Khan, A., Proc. Natl. Conf. Clays, Clay Minerals, 6th, Berkeley, 220).